void ITableDeclaration::check(const Names & column_names) const
{
const NamesAndTypesList & available_columns = getColumnsList();
if (column_names.empty())
throw Exception("Empty list of columns queried. There are columns: " + listOfColumns(available_columns),
ErrorCodes::EMPTY_LIST_OF_COLUMNS_QUERIED);
const auto columns_map = getColumnsMap(available_columns);
using UniqueStrings = google::dense_hash_set<StringRef, StringRefHash>;
UniqueStrings unique_names;
unique_names.set_empty_key(StringRef());
for (const auto & name : column_names)
{
if (columns_map.end() == columns_map.find(name))
throw Exception("There is no column with name " + name + " in table. There are columns: " + listOfColumns(available_columns),
ErrorCodes::NO_SUCH_COLUMN_IN_TABLE);
if (unique_names.end() != unique_names.find(name))
throw Exception("Column " + name + " queried more than once",
ErrorCodes::COLUMN_QUERIED_MORE_THAN_ONCE);
unique_names.insert(name);
}
}
void ITableDeclaration::check(const NamesAndTypesList & columns, const Names & column_names) const
{
const NamesAndTypesList & available_columns = getColumnsList();
const auto available_columns_map = getColumnsMap(available_columns);
const NamesAndTypesMap & provided_columns_map = getColumnsMap(columns);
if (column_names.empty())
throw Exception("Empty list of columns queried. There are columns: " + listOfColumns(available_columns),
ErrorCodes::EMPTY_LIST_OF_COLUMNS_QUERIED);
using UniqueStrings = google::dense_hash_set<StringRef, StringRefHash>;
UniqueStrings unique_names;
unique_names.set_empty_key(StringRef());
for (const String & name : column_names)
{
NamesAndTypesMap::const_iterator it = provided_columns_map.find(name);
if (provided_columns_map.end() == it)
continue;
NamesAndTypesMap::const_iterator jt = available_columns_map.find(name);
if (available_columns_map.end() == jt)
throw Exception("There is no column with name " + name + ". There are columns: "
+ listOfColumns(available_columns), ErrorCodes::NO_SUCH_COLUMN_IN_TABLE);
if (it->second->getName() != jt->second->getName())
throw Exception("Type mismatch for column " + name + ". Column has type "
+ jt->second->getName() + ", got type " + it->second->getName(), ErrorCodes::TYPE_MISMATCH);
if (unique_names.end() != unique_names.find(name))
throw Exception("Column " + name + " queried more than once",
ErrorCodes::COLUMN_QUERIED_MORE_THAN_ONCE);
unique_names.insert(name);
}
}
InterpreterSelectWithUnionQuery::InterpreterSelectWithUnionQuery(
const ASTPtr & query_ptr_,
const Context & context_,
const Names & required_result_column_names,
QueryProcessingStage::Enum to_stage_,
size_t subquery_depth_,
bool only_analyze,
bool modify_inplace)
: query_ptr(query_ptr_),
context(context_),
to_stage(to_stage_),
subquery_depth(subquery_depth_)
{
const ASTSelectWithUnionQuery & ast = typeid_cast<const ASTSelectWithUnionQuery &>(*query_ptr);
size_t num_selects = ast.list_of_selects->children.size();
if (!num_selects)
throw Exception("Logical error: no children in ASTSelectWithUnionQuery", ErrorCodes::LOGICAL_ERROR);
/// Initialize interpreters for each SELECT query.
/// Note that we pass 'required_result_column_names' to first SELECT.
/// And for the rest, we pass names at the corresponding positions of 'required_result_column_names' in the result of first SELECT,
/// because names could be different.
nested_interpreters.reserve(num_selects);
std::vector<Names> required_result_column_names_for_other_selects(num_selects);
if (!required_result_column_names.empty() && num_selects > 1)
{
/// Result header if there are no filtering by 'required_result_column_names'.
/// We use it to determine positions of 'required_result_column_names' in SELECT clause.
Block full_result_header = InterpreterSelectQuery(
ast.list_of_selects->children.at(0), context, Names(), to_stage, subquery_depth, true).getSampleBlock();
std::vector<size_t> positions_of_required_result_columns(required_result_column_names.size());
for (size_t required_result_num = 0, size = required_result_column_names.size(); required_result_num < size; ++required_result_num)
positions_of_required_result_columns[required_result_num] = full_result_header.getPositionByName(required_result_column_names[required_result_num]);
for (size_t query_num = 1; query_num < num_selects; ++query_num)
{
Block full_result_header_for_current_select = InterpreterSelectQuery(
ast.list_of_selects->children.at(query_num), context, Names(), to_stage, subquery_depth, true).getSampleBlock();
if (full_result_header_for_current_select.columns() != full_result_header.columns())
throw Exception("Different number of columns in UNION ALL elements:\n"
+ full_result_header.dumpNames()
+ "\nand\n"
+ full_result_header_for_current_select.dumpNames() + "\n",
ErrorCodes::UNION_ALL_RESULT_STRUCTURES_MISMATCH);
required_result_column_names_for_other_selects[query_num].reserve(required_result_column_names.size());
for (const auto & pos : positions_of_required_result_columns)
required_result_column_names_for_other_selects[query_num].push_back(full_result_header_for_current_select.getByPosition(pos).name);
}
}
for (size_t query_num = 0; query_num < num_selects; ++query_num)
{
const Names & current_required_result_column_names
= query_num == 0 ? required_result_column_names : required_result_column_names_for_other_selects[query_num];
nested_interpreters.emplace_back(std::make_unique<InterpreterSelectQuery>(
ast.list_of_selects->children.at(query_num),
context,
current_required_result_column_names,
to_stage,
subquery_depth,
only_analyze,
modify_inplace));
}
/// Determine structure of the result.
if (num_selects == 1)
{
result_header = nested_interpreters.front()->getSampleBlock();
}
else
{
Blocks headers(num_selects);
for (size_t query_num = 0; query_num < num_selects; ++query_num)
headers[query_num] = nested_interpreters[query_num]->getSampleBlock();
result_header = headers.front();
size_t num_columns = result_header.columns();
for (size_t query_num = 1; query_num < num_selects; ++query_num)
if (headers[query_num].columns() != num_columns)
throw Exception("Different number of columns in UNION ALL elements:\n"
+ result_header.dumpNames()
+ "\nand\n"
+ headers[query_num].dumpNames() + "\n",
ErrorCodes::UNION_ALL_RESULT_STRUCTURES_MISMATCH);
for (size_t column_num = 0; column_num < num_columns; ++column_num)
{
ColumnWithTypeAndName & result_elem = result_header.getByPosition(column_num);
/// Determine common type.
DataTypes types(num_selects);
for (size_t query_num = 0; query_num < num_selects; ++query_num)
types[query_num] = headers[query_num].getByPosition(column_num).type;
result_elem.type = getLeastSupertype(types);
/// If there are different constness or different values of constants, the result must be non-constant.
if (result_elem.column->isColumnConst())
{
bool need_materialize = false;
for (size_t query_num = 1; query_num < num_selects; ++query_num)
{
const ColumnWithTypeAndName & source_elem = headers[query_num].getByPosition(column_num);
if (!source_elem.column->isColumnConst()
|| (static_cast<const ColumnConst &>(*result_elem.column).getField()
!= static_cast<const ColumnConst &>(*source_elem.column).getField()))
{
need_materialize = true;
break;
}
}
if (need_materialize)
result_elem.column = result_elem.type->createColumn();
}
/// BTW, result column names are from first SELECT.
}
}
}